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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the color removal from congo red with hydrogen peroxide catalyzed by supported zirconium oxide (2000)
    Springer
    Transition metal chemistry 25 (2000), S. 599-604 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of the oxidative color removal from congo red dye using H2O2 in conjunction with transition metal ions supported on ZrO2 were studied. The rate of reaction is first order on H2O2, the catalyst, and in congo red. It attains a limiting rate at higher concentrations of reagent. Also, the rate of reaction decreases with increasing [H+], due to protonation of the substrate amino groups, as well as to the low deprotonation constant of H2O2 in acid medium. Addition of KCl to the mixture increased the rate of reaction. The catalytic activity of the catalysts lies in the following order: AgI 〉 CuII 〉 HgII 〉 CoII 〉 MnII 〉 FeIII 〉 NiII 〉 ZrO2 which is correlated with the redox potential, mg loading and % surface content of the supported metal ions. A probable mechanism for the oxidation processes has been suggested, which is consistent with the experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007008808372
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  • 2
    Electronic Resource
    Electronic Resource
    Catalytic activity of a zirconium(IV) oxide surface supported with transition metal ions (2000)
    Springer
    Transition metal chemistry 25 (2000), S. 260-264 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of H2O2 decomposition have been investigated using ZrO2 supported with transition metal ions including CuII, AgI, HgII, CoII, MnII, NiII and FeIII. At pH = 6.8, the reaction rate exhibits a first order dependence on the initial H2O2 concentration at low concentrations. The order of activity of the different catalysts is strongly dependent on the [H2O2]0 used. The reaction proceed via the formation of the peroxo-intermediate which has an inhibiting effect on the reaction rate. The rate increases with increasing pH, and attains a limiting rate at higher pH's. A reaction mechanism is proposed involving liberation of HO2 radicals from the peroxo-intermediate as the rate-determining step.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007041700160
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  • 3
    Electronic Resource
    Electronic Resource
    Catalytic Decomposition of H2O2over Supported ZnO (2000)
    Springer
    Monatshefte für Chemie 131 (2000), S. 1139-1150 
    Details
    ISSN: 1434-4475
    Keywords: Keywords. Hydrogen peroxide; Zinc oxide; Transition metal ions; Decomposition; Kinetics; Catalysts.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  Transition metal sulfates of Cu(II), Co(II), Ni(II), Cr(III), Mn(II), and Fe(III) supported on ZnO were prepared and characterized by SEM, EDX, and XRD. The kinetics of the heterogeneous decomposition of H2O2 over these supported catalysts was investigated. The reaction rate is correlated with both the amount of supported metal ion and its redox potential. The rate of reaction increases with increasing initial concentration of H2O2, attains a maximum, and decreases thereafter. It also increases with pH and reaches a maximum at high pH values. A reaction mechanism is proposed that implies the formation of a peroxo intermediate at the early stages of the reaction. A second intermediate is assumed to be formed at high [H2O2]o which inhibits the progress of the reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007060070021
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  • 4
    Electronic Resource
    Electronic Resource
    The catalytic effect of transition metal-ion ammine complexes on the decomposition of hydrogen peroxide in the presence of Dower-50W resin in aqueous medium (1987)
    Springer
    Transition metal chemistry 12 (1987), S. 51-55 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The kinetics of the catalytic decomposition of hydrogen peroxide was studied in the presence of Dowex-50W resin in the form of some transition metal-ion ammine complexes in an aqueous medium. The transition metal-ions, Co2+, Ag+, Cd2+ and Zn2+ were chosen in this study and the rate constants (per gram of dry resin) were evaluated at various resin weights in the 25–40°C range. A coloured compound (peroxo-metal complex), which formed at the beginning of the reaction in each case, was found to contain the catalytic active species. Probable mechanisms for the reactions are proposed. The activation energy and the change in the entropy of activation increased in the following sequence: [Ag(NH3]2]+〈 [Cd(NH3)6]2+〈[Co(NH3)6]2+〈[Zn(NH3)6]2+, which is also the probability sequence for the formation of the activated complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01023132
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the homogeneous reaction between some manganese(III)-Schiff base complexes and hydrogen peroxide in aqueous and sodium dodecyl sulphate solutions (1995)
    Springer
    Transition metal chemistry 20 (1995), S. 494-497 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The kinetics of the reaction between H2O2 and some Schiff base complexes of MnIII have been investigated in both aqueous and micellar sodium dodecyl sulphate (SDS) solution. The reaction rate is first order in both H2O2 and [complex], and inversely proportional to [H+]. The second-order rate constant increases in the sequence [Mn(salophen)(OAc)] 〉 [Mn(salen)(OH2)]-ClO4 〉 [Mn(salen)(OAc)]H2O, where salen = N,N′-bis-(salicylidene)ethylenediamine and salophen = N,N′-bis-(salicylidene)-o-phenylenediamine. At SDS concentrations below the critical micellar concentration, there is almost no effect on the rate of reaction whereas at higher concentrations the reaction rate increases slightly. A mechanism involving MnII and a peroxo intermediate is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00141524
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  • 6
    Electronic Resource
    Electronic Resource
    Catalytic decomposition of hydrogen peroxide in the presence ofN, N ′-bis(salicylidene)-o-phenylenediamineiron(III) sorbed on to Dowex-50W resin (1991)
    Springer
    Transition metal chemistry 16 (1991), S. 319-323 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The tetradentate Schiff-base ligandN, N ′-bis(salicylidene)-o-phenylenediamine (salph) is very strongly sorbed by cation exchange materials with transition metal counter ions, forming stable complexes. The kinetics of catalytic decomposition of H2O2 in the presence of (salph)-FeIII sorbed on Dowex-50W resin has been studied in aqueous medium. The reaction is first order with respect to [H2O2]. The rate constant, k (per g of dry resin) decreased with increasing degree of resin cross-linkage due to a salting out effect. The activation parameters were calculated and a reaction mechanism is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01024073
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  • 7
    Electronic Resource
    Electronic Resource
    A kinetic study of the homogeneous oxidation of hydroxylamine by manganese(III)-bis(salicylaldimine) complexes (1995)
    Springer
    Transition metal chemistry 20 (1995), S. 312-315 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The kinetics of the oxidation of hydroxylamine by manganese(III)-bis (salicylaldimine) complexes have been studied over the 5.2–8.4 pH range. The reaction is first order in both hydroxylamine and oxidant, and inversely proportional to [H+]. The [complex]: [hydroxylamine] stoichiometric ratio is 1∶1 in both acidic and neutral media, and 2∶1 in an alkaline medium. The second-order rate constant increased in the sequence: [MnIII(L2)OH2]-ClO4·2H2O 〉 [MnIII(L1)OH2]ClO4 〉 [MnIIIL1)OAc]-H2O. The reactivity of unprotonated hydroxylamine is much higher than that of the protonated form. The reaction rate decreased significantly with addition of chloride ions. A plausible mechanism is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00143500
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  • 8
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the oxidation of L-ascorbic acid by the N,N′-ethylenebis(salicylideneiminato)manganese(III) complex in aqueous solution (1996)
    Springer
    Transition metal chemistry 21 (1996), S. 130-134 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The kinetics of oxidation of l-ascorbic acid by the N,N′-ethylenebis(salicylideneiminato) manganese(III) complex have been studied over the 4.5–9.3 pH range. An intermediate ascorbate complex was formed which had an inhibiting effect on the rate of the redox reaction. The rapid formation of this intermediate was followed using the stopped-flow technique, whereas its slow decomposition was monitored using a conventional spectrophotometer. The formation of this intermediate was strongly pH dependent. Addition of sodium perchlorate and sodium dodecyl sulphate (anionic surfactant) affected the reaction rate. A probable mechanism comprising both the intermediate formation and the overall redox reaction is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00136542
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  • 9
    Electronic Resource
    Electronic Resource
    Kinetics and mechanism of the copper(II) catalyzed oxidation of N-substituted p-phenylenediamines by 2,3,9,10-tetramethyl-1,4,5,7,8,11,12,14-octaazacyclotetradeca-1,3,8,10-tetraenecopper(II) (1999)
    Springer
    Transition metal chemistry 24 (1999), S. 511-516 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of oxidation of N,N-dimethyl- and N,N,N′,N′-tetramethyl-p-phenylenediamines, to the corresponding semiquinonediimine radical and the quinonediimine, with a macrocyclic copper(II)-complex were studied at pH ≤ 7. Under pseudo-first order conditions, the reaction rate for the N,N,N′,N′-tetramethyl derivative was much faster than for N,N-dimethyl-p-phenylenediamine, due to the increased probability of electron transfer. The reaction rate decreases with increasing acidity of the medium as a result of protonation of the amine nitrogen atoms. The rate constants and activation parameters were evaluated and the reaction was found to be enthalpy controlled. Furthermore, kinetic measurements revealed a remarkable superadditive effect when CuCl2 solution was added, even at concentrations lower than that of the copper complex. This observation was used for the kinetic determination of copper ions at concentrations  〈 10−5M.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006935718594
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  • 10
    Electronic Resource
    Electronic Resource
    Kinetics of hydrogen peroxide decomposition with Fe(III) and Cr(III)-ethanolamines complexes sorbed on dowex-50W resin (1995)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 27 (1995), S. 499-505 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the H2O2 decomposition in presence of Fe(III)- and Cr(III)-complexes of mono-, di-, and triethanolamine supported on Dowex-50W resin have been investigated. The decomposition process proceeded with first-order kinetics for the substrate concentration. The rate of reaction increased with increasing number of the coordinated ligands in the metal complex as well as with increasing ligand basicity. The decomposition reaction involved the formation of an intermediate active species, which converts into a peroxo-metal complex of brown, green, or gray color. A mechanism describing the decomposition process is proposed. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550270508
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